That sounds very tough to navigate. I definitely have an advantage over you in trying to find time to myself. Not near as many precious relationships that I am obligated to whom are just as deserving as my time as I am. I think that one day I will surely discover that this time is maybe even more valuable when interrupted by delightful little distractions like a wife and children.
It is surely a tough balance to find, because I know both are important and immeasurably valuable in their own rights. But I also have learned that I am incapable of enjoying either my “selfish time” or time with meaningful relationships if I struggle to adapt to the changes that inevitably and invariably happen in a day. The surest way to stress out is to be inflexible, because you are so right. There are so many things that change, and the needs for each day vary, and it is very possible to plan too much and have too high of expectations for your morning or work flow.
I think the real goal here is a calm and adaptive frame of mind that can aim at intentionality of time but still rejoice in the joyful distractions, and the flex to meet the needs of the unexpected opportunities or problems to solve in a day.
If you find that harmony, please let me know. Until then, we will both wrestle to discover it, but that wrestling is worth while.